It may be necessary to provide optical components with sharp-edged structures for application or production reasons. For example, it may be of advantage to introduce stray light edges into an optical component in order to prevent unwanted stray light or extraneous light in light-guiding regions of the component. Such stray light edges and corners must under some circumstances be formed with sharp edges because of their function, i.e. they must not have any or only a very slight rounding—that is to say only a very small radius of curvature. Sharp edges may additionally also occur for process-related reasons, for example during injection molding. The sharp edges may in this case either be formed concavely (included angle of the areas bordering the edge of less than 180°) or convexly (included angle of the areas bordering the edge of greater than 180°).
Furthermore, optical components often have to be provided with functional layers by means of coating processes. Primer layers, which serve for example for promoting adhesion, and hard layers, for increasing the mechanical resistance of the surface of the component, may be mentioned here by way of example. In the region of a concave sharp edge or corner, the application of coatings in wet coating processes may be problematic, since an accumulation of coating material may occur in the region of the edge or corner because of the surface tension. Since, as a result, the coating thickness at this point is much greater than on the adjacent areas, in the case of many of the coatings that are typically used this can lead to the formation of cracks or even to the coating peeling off or coming away (delamination) because of a buildup of stress. The often used polysiloxane-based hard layers are susceptible to this in particular. But purely polymer-based lacquers, such as those used as primer layers, may also display similar phenomena if the thickness of the layer is too great. In addition, with a convex sharp edge or corner there may be a thinning of the coating material at the edges, that is to say a flowing away from the edge or corner, which in turn has the result that the thickness of the layer may be too little in the region of this edge.
This is not only critical with regard to the durability of the layers, but may also lead to contaminants or the like in subsequent processes, and in addition to impairments and optical defects, for example due to inhomogeneous and/or incomplete drying. With an inhomogeneous layer thickness, it may be that the primer or hard lacquer for example would influence the optical properties of the stray light edge or the adjacent areas (for example by forming a meniscus of the primer layer or hard layer, etc.). On the other hand, it is often of great advantage for the application of the hard lacquer if the complete component can be coated.